Abstract

High density fine grain ceramics were successfully prepared by two-step sintering and their ferroelectric properties were investigated. Experimental evidence indicates the existence of a morphotropic phase boundary at the composition , which exhibits a piezoelectric coefficient of 700 pC/N at room temperature, significantly higher than the reported values to date. Furthermore, a higher electromechanical coupling factor and a larger remnant polarization were obtained. The paraelectric-to-ferroelectric phase transition occurs at , slightly lower than in the coarse grain ceramics with a similar composition, suggesting a grain size effect. The local effective piezoelectric coefficient was estimated to be 795 pC/N at 2.29 V, measured by scanning probe microscopy. Further atomic force microscope observation revealed the existence of domains of about 60–70 nm in width, confirming the previous results that small domain structure enhances the piezoelectric properties.

Received 12 April 2008Accepted 01 September 2008Published online 13 November 2008

Acknowledgments:

The authors appreciate the financial support by National Science Fund for Distinguished Young Scholars (Grant No. 50625204), Science Fund for Creative Research Groups (Grant No. 50621201), National Natural Science Foundation of China (Grant No. 50472006), and the Ministry of Sciences and Technology of China through 973-Project under Grant No. 2009CB623301 and through 863-Program under Grant No. 2006AA03Z428. We would also like to express our special thanks to Professor I-Wei Chen, University of Pennsylvania for helpful discussions.